Apparatus conventionally employed in forming twisted conductor units have an arcuate, tubular bow through which the conductors are passed that is revolved about a space in which either a set of conductor supply reels or a conductor unit take-up reel is located. Where the apparatus has the capability of forming twisted conductor units of different twist lengths, that is with different numbers of twists for a given length, it must be provided with means for varying the speed of the bow relative to the speed of advance or line speed of the conductors. This may, of course, be done by varying bow speed. However, anything less than maximum bow speed adversely limits production since the faster the bow speed the greater the number of twists which may be formed in any given period of time.
Because of the just described limitation it has been more common for the apparatuses to include means, such as a variable speed capstan, by which to vary line speed. This has performed well on twisters of the type having the conductor unit take-up reel located externally of the space about which the bow revolves. These external take-up machines however have other disadvantages and limitations. For example, multiple supply reels must be located within the bow orbit together with means for cotrolling conductor tension. This in turn mandates the use of an enlarged bow and bow orbit which, because of the increase in mass and angular acceleration forces, restricts bow speed. For these reasons it is desirable to locate the conductor supply reels externally and the twisted conductor unit take-up reel internally of bow orbit. To do so while providing the capability of producing different twist lengths would thus be quite desirable, particularly so if such could be done without locating take-up reel drive, capstan gearing, slip clutch assemblies and the like within the bow orbit. It therefore, is to this task to which the present invention is primarily directed.